Eyewitness evidence is arguably one of the most frequent and important types of evidence encountered in a criminal case. Eyewitness testimony has demonstrated to have an enormous impact in the criminal field as it contributes immensely to the conviction of an individual. However, eyewitness error is one of the leading causes of wrongful convictions. For example, the United States has seen more than 250 DNA exonerated cases (where DNA has proved the innocence of a convicted prisoner), and alarmingly, eyewitness error occurred in more than 75% of these cases, thus making it the primary contributing factor to wrongful convictions (Wise et al., 2009; Innocence Project, n.d.).
Our memories are malleable, such that they can be altered or influenced by post-event information like behavioural cues. Behavioural cues can be verbal (wording of a question) or nonverbal (such as gestures). A great deal of research has shown the tremendous impact verbal influence has on eyewitness memory. To illustrate this further, let us briefly turn to a study by Elizabeth Loftus and John Palmer (1974). In this study, participants were required to watch a short video of a car accident and answer questions following the clip. One of the tasks was to identify how fast the cars were going. However, when the researchers manipulated the verb (e.g. “how fast were the cars going when they smashed/bumped/hit/contacted?”), participants who were asked how fast the cars were going when they smashed estimated the cars to be traveling approximately 40.8 mph. Interestingly, when participants were asked how fast the cars were going when they contacted, the estimation of speed dropped to 31.8 mph (Loftus & Palmer, 1974). This research is critical as it demonstrates how simple manipulation of the verb in a sentence can impact an individual’s memory and response, supporting the flexibility of our memories and how they can be influenced by verbal cues.
Nonverbal Influences: What the research tells us.
Without question, most of the scientific research regarding eyewitness memory focuses on verbal influences. Therefore, it is imperative that we turn our attention to nonverbal influences (gestures) in order to determine if such behavioural cues have a similar effect on eyewitness memory. In fact, when accompanying the question “did the suspect have facial hair?” with a beard gesture, witnesses incorporated the information presented through the gestures into their original memory of the event, such that they reported seeing a beard (Gurney, 2015). Through his research, Daniel Gurney (2015) successfully demonstrates that nonverbal influences are comparable to verbal influences, such that misinformation (false information) can be conveyed through gestures and speech. In his study, Gurney (2015) had 92 participants watch a video of a staged crime. The clip showed a girl waiting at a bus stop when a man entered and stole a phone from the bag on the ground beside her. A few bystanders were present in order to have the scene appear as real as possible. Next, participants were asked critical questions about the video regarding the victim’s appearance, the stolen item, where the suspect put the item, etcetera, while being provided with verbal or nonverbal suggestions.
These suggestions included factual information (information congruent with the crime scene) or misleading information (information that was false). The verbal questioning conditions presented the critical information through speech. For example: “the item stolen was a phone” (factual), or “the item stolen was an iPod” (misleading). The nonverbal questioning conditions presented the critical information through gestures, while the speech remained unbiased. For example: “an item was stolen” + phone gesture (factual), or “an item was stolen” + iPod gesture (misleading). A control condition was used, which involved the interviewer asking unbiased questions without any gestures, for example, “an item was stolen”. Participants were required to respond with a “correct”, an “incorrect”, or an “I don’t know” response.
Factual Information vs. Misleading Information:
The results indicate that individual responses were affected by the type of questioning. Therefore, when presented with factual information, participants were more likely to give a correct response. Nonetheless, when presented with misleading information, participants were more likely to give an incorrect response. This is crucial to note because, with regards to eyewitness testimony, officers do not usually know the correct facts (hence statements gathered from witnesses). Therefore, if officers fail to ask open ended questions, they could potentially influence the memory of the eyewitness. For example, if an individual witnessed the crime shown in the experiment and could not remember what was stolen out of the bag, but the officer asked if it was an iPod (instead of asking openly, “what was stolen?”), it is probable that the eyewitness could have been influenced, leading them to recall that the stolen item was an iPod, thus providing inaccurate conclusions. Interestingly, the verbal and nonverbal misleading groups differed significantly from the control group. What this means, is that unbiased questioning in the control group elicited more correct responses, whereas misleading questions or gestures led to more incorrect responses. So in order to increase the likelihood of obtaining correct or accurate responses, it is best to ask unbiased questions, allowing the eyewitness to freely recall the event from memory without any behavioural influences.
So, is there a difference between verbal and nonverbal influences?
No. Verbal and nonverbal influences do not differ significantly from each other. However, the absence of variation among the two should not to be overlooked. In fact, what this means is that nonverbal cues (gestures) are just as likely to influence memory as verbal cues. This is imperative to understand because whereas speech is easier to control and standardize, gestures are harder to inhibit. We have already seen a well-established verbal misinformation effect, such that when presented with misleading information, people are more likely to give an incorrect/inaccurate response. So, if gestures are just as likely to influence responses, this increases the impact of behavioural influence on eyewitness memory. Further, it has been suggested that people integrate information from gestures into speech; eyewitnesses may use information from gestures to reconstruct their memory. For example, when presented with the statement “my brother went to the gym” with a “shooting a basketball” gesture, listeners actually extracted the “basketball” information from the gesture, but also remembered it as part of the speech (Gurney, 2015). Gestures are an important part of human communication and may be automatic or implicit, occurring outside of our awareness, thus harder to control.Therefore, suggesting the ability of gestures to influence one’s memory, making them critical candidates for influence in eyewitness memory and error, potentially leading to wrongful convictions.
This information can prove to be useful for law enforcement, should they be provided with this knowledge. Having said that, education and training programs can be created to raise awareness of behavioural influence. Further, understanding how easily memory can be altered by not only verbal cues, but nonverbal cues as well, is crucial for law enforcement, especially when eyewitness testimonies have a major effect on convicting an individual. Such programs can aid officers in asking open ended questions, along with helping them develop strategies in attempt to control the use of gestures. However, as mentioned previously, gestures sometimes occur without awareness, proving to be difficult to eliminate or inhibit. As such, it might be more beneficial to create a standardized method to ensure the reduction or elimination of behavioural influences, thereby reducing eyewitness error, ultimately reducing wrongful convictions.
- Brittany Haynes
Gurney, D.J., (2015). What’s left unsaid: How nonverbal influence compares with verbal influence. Psychiatry, Psychology and Law, 22 (3), 465-473. doi: http://dx.doi.org/10,1080/13218719.2014.985624
Loftus, E.F., & Palmer, J.C., (1974). Reconstruction of automobile destruction: An example of interaction between language and memory. Journal of Verbal Learning and Verbal Behavior, 13 (5), 585-589. Retrieved from PsycINFO
Wise, R.A., Pawlenko, N.B., Safer, M.A., & Meyer, D., (2009). What US prosecutors and defence attorneys know and believe about eyewitness testimony. Applied Cognitive Psychology, 23, 1266-1281. doi:10.1002/acp.1530